基于独立分量的信息极大化法机械振动盲分离研究

基于最大信息化原理,建立了用独立分量分析方法估计分离矩阵的自适应算法.利用所建立的方法进行了数值仿真,分离后信号波形与源信号一致.对具有不同转速的调速电机进行了多传感器信号采集并进行盲分离,电机的频率被有效的区分开来.实例证明,该方法是分离机械振动信号的一种有效方法.     

两种减隔震支座性能对比研究

通过对摩擦摆支座及弹塑性钢阻尼支座两种不同类型的减隔震支座的抗震性能进行对比,选择适合项目要求的支座类型。对比结果表明:两种减隔震支座均能够有效延长桥梁结构自振周期,支座横向刚度较小的摩擦摆支座更有利于周期的延长,同时产生的墩顶剪力也较小;对于墩底截面及基顶截面的弯矩和剪力,在墩高较低时横向刚度小的摩擦摆支座减隔震性能较好,而墩高大于20 m时,横向刚度大的弹塑性钢阻尼支座更有优势。     

城市轨道交通预制板轨道弹性部件的研制及应用

在轨道交通领域,传统的浮置板轨道系统均存在施工程序繁杂、更换困难等问题。针对以上问题,以预制板橡胶包套为研究对象,从预制道床板系统配套设计、减振橡胶包套生产制造这两个方面进行合理组合和优化设计,开发出一种新的减振垫预制板系统,同步形成产品设计优化、制造工艺条件以及验收标准等成套技术。通过系统的材料、工艺、装配设计、室内试验和优化改进,并通过实际工程示范应用,施工综合进度提高50%以上,减振效果大于10.0 dB。     

减振器冲击性能测试方法研究

根据舰船所受到的冲击力学过程,对减振器冲击性能测试问题进行了分析,提出了基于气缸式冲击模拟台的减振器冲击性能测试方法,并介绍了试验测量系统.采用该方法对钢丝绳减振器作为冲击防护元件时的力学特性进行了研究,得出了该元件关于压缩/拉伸非对称的冲击耗能特性,并分析了参数变化特点.     

长洲船闸阀门抗振及抑制空化措施研究

长洲三线四线船闸采用特大型平面输水阀门,阀门平面尺度4.6 m×6.0 m,远超国内外水平,空化和振动问题十分突出,其阀门抗振动和防空化措施是该船闸群建设中的一项重大关键技术难题。通过原型观测,检验了模型研究提出的阀门抑制空化及抗振措施效果,取得了满意的调试成果。     

板岩结构中隧道爆破施工技术

结合新建赣州至韶关铁路黄竹头隧道工程,通过深入调查研究并总结其板岩结构的地质特性、阐述了针对不同的板岩结构,如何通过正确的爆眼设计和爆破技术获得较好的爆破效果,减少对软弱围岩的扰动和硬质围岩中遗留岩体的损伤,研究结果对今后类似地质条件的隧道爆破施工有一定的参考价值     

Effects of the guideway's vibrational characteristics on the dynamics of a Maglev vehicle

The levitation control system in an electromagnetically levitated vehicle controls the voltage in its winding to maintain the air gap, which is the clearance between the electromagnet and the guideway, within an allowable range of variation, while strongly interacting with the flexible guideway. Thus, the vibrational characteristics of the guideway play an important role in the dynamics of Maglev (magnetically levitated) vehicles that utilise an active electromagnetic suspension system. In this study, the effects of the guideway's vibrational characteristics, such as natural frequency and damping, on the dynamics of the Maglev vehicle UTM-02 are numerically and experimentally analysed. From these analyses, the coupled equations of motion of the simplified vehicle–guideway model with three degrees of freedom are derived. Eigenvalues are calculated and frequency response analysis is also performed, in order to obtain a clear understanding of the dynamic characteristics resulting from the guideway's vibrational characteristics. To verify the numerical results, air gap tests of the urban Maglev vehicle UTM-02 are also carried out. These results lead us to recommend that the natural frequency of the guideway be decreased by increasing mass density rather than by decreasing rigidity, and that its damping ratio be increased in the Maglev vehicle UTM-02 employing a five-state feedback control law as a levitation control law.     

On vehicle/track impact at connection between a floating slab and ballasted track and floating slab track's effectiveness of force isolation

When a vehicle runs over the connection between a floating slab track (FST) and ballasted track, wheel/rail impact may occur because of the stiffness difference in the two kinds of track, and thus a transition sector is usually included at the connection to smoothen the stiffness change. This phenomenon is studied by numerical simulation using a time-domain model for an idealised case without such a transition to determine whether it is actually necessary. Calculation results show that the wheel/rail impact load is moderate for a light FST and increases with the vehicle speed or decreasing the natural frequency of the FST. From simulation the wheel/rail parametric excitation is observed, as a result of variation in the stiffness of the FST with the period of the single slab length. The wheel/rail load due to the parametric excitation also increases with the vehicle speed. In addition, good performance of vibration isolation can be seen for the FST in terms of the force transmitted to the infrastructure.     

On the interest of integrating vehicle dynamics for the ground propagation of vibrations: the case of urban railway traffic

This paper presents a complete numerical model for studying the vertical dynamics of the vehicle/track interaction and its impact on the surrounding soil, with the emphasis on vehicle modelling. A decoupling between the track and the soil is proposed, due to the difficulty of considering all the subsystem components. The train/track model is based on a multibody model (for the vehicle) and a finite element model (for the track). The soil is modelled using an infinite/finite element approach. Simulations of both models are carried out in the time domain, which is better able to simulate the propagation of the vibration waves and to take into account the possible nonlinearity of a component. The methodology is applied in the case of an urban tram track and validated with the available experimental data. Models for the tram, the track and the soil are described. Results from the complete model of the vehicle and a simple model, based on an axle load, are compared with experimental results and the benefits of a complete model in the simulation of the ground vibration propagation induced by railway vehicles are demonstrated. Moreover, a parametric study of the vehicle wheel type is conducted, which shows the advantage of a resilient wheel, for various rail defects.     

A study on the effect of different tyre imperfections on steering wheel vibration

Multibody dynamics and tyre models have made possible detailed analysis not only for ride and handling, but also for determining their effects on tyre nonuniformities. The aim of this paper is to analyse the steering wheel vibration, both shimmy and shake, excited by different tyre imperfections by using the commercial simulation package ADAMS/car 2005R2 and FTire. Different settings with respect to imperfection locations, amount, and the combined effects of defects have been studied. An interesting beat phenomenon is observed when all the wheels have imperfections. A procedure to determine the type of imperfections in the tyre from the results of the test rig has also been proposed.